High frequency tubes and circuits



Aug. 17, 1943. G. E. PRAY ETAL 2,326,801

HIGH FREQUENCY TUBES AND CIRCUITS Original Filed Sept. 22, 1938 PatentedAug. 17, 1943 'snan mizqiinncy Geor ge E rrflay aiid sebastanmwatoaeg riv -"riginal app1ica;ti0n September 22. 195 8, .saia' "fl $31 ,215,-mwtmatem -NQ.- 2,,2514951, iaatea. r 1

A gust 19.41 '1) anua y 122,; 1 3

This invention relates to vacuumftuhesffofu e with ultrahigh radioincluding such tubes. I

Among the several are:

To provide vacuum tubes in :iivliichi catho' grid transit time lossesare' reduedtbaQni mum;

To provide vacuum tubes .-ne arly ele t cns nrfihe aihed= 3 form pathlengths for grid space;

To eliminate ture; g: g .1, 1:5 To provide vacuum tubeswith high shunimp dan si I 3.2,.

To .providevacuum tubes with electrode capacities;

objects of etk a e eddy eurrents'in' man a I To provide, .in .vacuunitubes t ti e-i br more beams of electrons,-.icontrollablehy, potentialsaplied to the tube-electrodes;

To provide circuitsand icperating: utilizing tubes of the-type.ahDVfl-=IHQDlIJ-DQ Q- :.-In the drawingz J Figs; 1 and 2 '.are,.respe.ctiyeb 5 section and .a .lon'gitudinalsection :of tube according.to .ounpresentinventitm Figrs iis a schematic I diagram ;-of;

te'ctor; f Fig. 4 illustrates the "use/010m tubeas :a mixer inconnection with alccal oscillation-i112.

Fig. 5 is a transversetsectionwof a tubei'accord-l ingto-our inventionhavingamultiple centre and having a focusing plate icon-direct; trons-to a.sing1e anode; "j

with its individual. 'contnol electnode push pull operati'on. 1;

This application is .a division I. use. n:

9f ourln oepen mg. application Ser. No. 23-1,'215,-fi1ed1 septentber zz19S8 Patent-No. 225L951, August,l2,gli94 l.' For amplification;detection; or osciilationizat positive. M My o H .the" istance. from thecathode to. thegi id'before transvefse.

Ea, duoid eda- 2 utilizing the above-mentioned. tube. as; aide-Q,

' for faflnormaispacing of" foruse'at'fnequencies aboveiltlfimegacycleswfatednegt ve'gridand positivean'ode (brjs'creen' it fusing fa --t etro;de or' pentodef); fictentials, thief" time requiz ed for "an electrrig-to .go; from-"the;

Fig.6 uti1izes thesame form omocusin -Qhte' as Fig.. 5, but has "twoseparate :a 'fld 935F15 frequencies of theorder 01 megacyciesxrpensecond and upward, --the vacuuiii tubeinput i n'ithe "emciency of thetube we e;

sacrifice in the resonant game: the the input elements of the tube alsoniese .a; low

' pedance'andthe'cathodeto gi i delecti'orr 'transit time are the mostimportant; factorsflimiting 1 circuit is application.

V greatly reducidQwithfuftheflossin Y sensitivity and lossbfseigctivityiff f Thisilowishuntresistance dueto 'tr'a;nsitti'nie tion;we will consider "a -vacuum 'tupe trioderw-ith an el'ecitrorii emittingcathode iorf'filament-fan j.

anode'whose potential is positive-with respect;

to the cathode, and a "contr:o1 'eieetrode b'r gridf w js im eniia is.va 'e isipu al re 1. tive to negative with'respect-tofthe(cathode;

' The cathode wilifen it a'suppljo'f elections with T aife'. faiwn frbmthe space charge layer, theyfar e H replenished by 'fu1 ther cathodeemission.- Since maintained positive, the 'pctential thefah'ode so"close I;

seem 2 the g di-""curi cut."is affected;- andffi om :cathode to beforethe fan'od'e' current; i s afiected.

Therit; it-uneq a isa y lowicq par' t mi anode l otentialfso {the,velocity inipaftedftcan electron in'thje cathod eagrid space'fisjverysmall compared jtcfthe'velofcity in .tjhefgifid-anode space. hu t e h d=er i m .v ma y:

times greater than the grid fnode; transitti ne I .1

he e ctrodesgandis the r important iafctor to consider; j;

- In "the vacuum tubes com'mercia y avai cathode jot, filament to thegrid 'is of" the rd'e T of 210: s eonds.'= f At fllow frequencies thise1 is" negligible com pa ed to "the period .0 oscillationfbut as thefrequency 'is' incre edtransittime 'becor nies'a larger-portion forheaters.

The component of current in phase with the negative gridvoltage has theefiect of greatly reducingtheinput impedance of the tube and consumingpower from the input circuit. f I

The electrode'materials used in our novel tubes may be any of those wellknown in the art as suitable for the various purposes, such as tungstenor nickel alloys for grids r controlfelectrodes;. I.

molybdenum or nickel alloys for anodes, suppressors, or focusingelectrodes; "nickel alloy sleeves coated with oxides of barium,strontium carbonate or thorium for cathodes, and tungsten.

All the electrodes are normallysupported and their spacing kept constantby} means of mica'discs at the ends of the electrodes. As hereinafterused, the term strip electrode is to be understood as designating andetector or mixer in a superhetero-dyne circuit. The circuit elementsare the same as in Fig. 3 except that the output impedance is here aresonant circuit comprising an inductance 45' and a capacitance 46; theoutputenergy being taken off through inductance 41 coupled to inductance45. The output impedance is-resonated to a desired intermediatefrequencyderived from beating the output of local oscillator 48 with the inputradia frequencyx In Fig. 5 the construction is modified byhav- ;,ing;asingle; anode 13, a single control grid 14, a single acceleration gridand a single focusing plate 'lli that extends around the cathode 58 inspaced relation thereto from adjacent one side of anode-13 to adjacentthe other side thereof,

" thus having at least three quadrants around the electrode whereof thelength is notably greater,

than the width and, if transversely curved, not subtend more than a-fewdegrees. V

The embodimen of our invention. shown in Figs ..l and 2 is aduo-diode'intended for opera does frequencies." Within the. glassenvelop is dis- Posed the, cathode. support 30 having electron emissivebodies 3| and 32 on diametrically'opposite sides thereof and'facing theemissiv bodies arethe electrodes 33and 34. The electrodes 33. and 34 areplaced yery close toi the respective emissive bodies, the spacingbetween an electrodeo and its coacting emissive' body being but a fewcathode enclosed by the focusing plate with the anode ,13 between theterminii of the plat It but outside. the 'spaceenclosed thereby. Whilethefocusing electrode could be extended to encloserall the electrodes;this is undesirable due tion as a detector or-rectifierat very highradio to the increase resultf Operation at high frequency usually makesit desirable'to utilize balanced, or push-pull input circuits, feedinginto a balanced tube circuit. In the case of a single sided tube, thatis, one having, one "control electrode and one anode, it is in outputcapacitancethat would necessary to use two tubes to obtain a balancedcircuit. The connection between the separate thousandthsof an inch; Theareasof thesurg faces of electrodes 33fand Mare substantially equal tothe areas of tlie'respective cbactin emissive bodies 31; and 32 and thesurfacesfiof the anodes are substantially uniformly spaced:

from the, surfaces of the emissivebodiesgwhreby electron paths ofluniformlllen'gth areprovided between the emissive bodies and the.electrodes.- The electrodes aa nc'u'may have widths of .of an inch and alength of /8 01 an'inchwhichj gives a low input cameraman the ordercross. micromicrofarad; giving satisfactory operation at frequenciesabove 500'megacycles persecond. A detector circuit employing the tube ofFigs.

1 and2is -shown schernatically in Fig. 3, whereinthe electrodes 33 and-34 are respectively con-,

nected to the parallel members35'and 3B of a resonant frame; This framecomprises the.mem-.

bers 3 5;and 3B; which may be-shortrods of conductive material havinglow resistance connected at .their end remote from the tube by albar 31,

; with. a conductive tuning. slider 38 contacting both bars. The bar t!is provided to reduce dead end losses and the slider, may be moved to.resonate the frame, as is well knownin this art. --A variablecapacitance 39 may be connected across the frame to provide additionaltuning if, desired. The input leadsto slider 38 aredesig- Y natedby tlland and bylmeans thereof the alternating potentials are applied" toelectrodes 33- and 34; The cathode bodies :31 and 32 are connectedthrough a suitable resistor lz to, the slider38 andthe-output leads 43areconnected to the opposite terminals of resistor 42 which may beshunted by a capacitance 44; This'circuit acts asa full'wave detectoriorrectifier; the radio fre-' 'quency signalsjbetween electrodes 33 and.34; h-j ing substantially 180 degreesout. of pliasefwith', each other,and the demodulated'output appears acrossthe'output impedance 42; 44.The resonant frame isfound to'be more advantageousthanfthe conventionalinductance for 'frequ cies above 200' megacycles'persecond; I

Fig.-4 depicts our duo-diode'used as theffirst anodes 11 and 18 and thecathode 150. In this.

tube the electron stream flows continuously toward the anodes,'but sincethe control electrodes l9 and have applied'to'them' radio frequencypotentials that differ substantially degrees in phase-the electrons willbe attractedto one anode and-kept away from the other during onehalfcycle and then attracted to. the, other and kept iaway'from the oneduring the next, half cycle. -It is thus seen that this tubeoperates asa'balanced or'push-pull unitwhile the electron stream continues to flowin the same gen:

eral direction; If Ldesired,z accelerating grids may-"beused'in :thistype of." tube. :A single vspace charge gridor a single: screentgridgorboth, should work satisfactorily withthe double elementsgof this tube..j

--Wherever in this; specification definite values are stated they. aregiven by way of illustration. and not. ..1imi iQ I he invention hereindescribed and claimed aybe used. a d. ma i sture by 'bi-fb t e Gvernment oi t Urine? States-ref new for governmental purposes withoutthe payment of-anyroyalties thereon ortn'e'reror;

'WefclainhI; v '1 'jl'." An"'electr on" f charge device, comprising acathode support; separate electron emisslve bod-' ies on opposite sidesthereof, each said body 1 subtending substantially less than 180 ofangle, means to cause said bodies to emit electrons, and

a separate electrode disposed closely adjacent to each of said bodies,said electrodes each having a surficial area substantially equal to thatof the respectively adjacent said body and being substantiallyequidistant in all parts of its surequal in area to the area of therespectively adjacent said electrode and substantially equidistant inall its parts from the corresponding parts of the surface of suchelectrode.

3. An electron dischargedevice, comprising a cathode support, stripelectrodes on opposite sides of said support and closely adjacentthereto, and separate electron emissive bodies on said supportrespectively adjacent each said electrode, said electrodes beingdisposed with a substantially uniform distance between each surfaceelement of said bodies and the corresponding opposed surface element ofsaid electrodes, said distance being sufficiently short that theelectron transit time from emissive body to'electrode is small comparedto the period of a wave having a frequency in excess of Y500 megacycles.

tunable toga desired transfer frequency connecting said bodies to saidframe at a. point sub stantially in electrical symmetry with respect tosaid frame, an oscillator operatively connected to produce inconjunctionwith thejinput frequency, the frequency to which said impedance istuned, and output means operatively associated I V with said impedance;

7. An electrondischarge device, comprising an electron emissive cathode,two narrow strip anodes disposed adjacent to but spaced from each otherparallel to and substantially equidistant from said'cathode on the sameside of said cathode, a control electrodebetween each said anode andsaidcathodafan'da focusing elec-' trode extending from adjacent one. ofsaid anodes around said cathode but spaced therefrom' and to a positionadjacent the other said anode."

8. An electron discharge device, comprising a cathode support, a narrowstrip electrode dis-- posed adjacent thereto, and an electronemissivebody on saidsupport, said body being disposed facing said electrode andhaving a surface area substantially equalto, that of said electrode, the

distances between all surface elements on-said.

body and the corresponding surface elements of said electrode beingsubstantially equal. 1

9. An electron dischar'gedevice,comprising an electron-emissive cathode,two narrow strip anodes disposed adjacent to but spaced from a eachother parallel toand substantially equi- 4. A circuit for high radiofrequencies, com-j prising a discharge device as set forth in claim 1,

a resonant frame having two parallel conductive members connectedtogether at their ends remote from said tube, means connecting the endof each of said members respectively to one,

of said electrodes, a tuning slider conductively connecting saidmembers, input means connected to said slider, common means including anoutput impedance connecting said bodies to said slider and output leadsconnected to opposite terminals of said impedance.

5. A circuit for'high' radio frequencies, com prising a discharge deviceas set forthin claim 1,

aresonant frame having two parallel conductive distant from said cathodeon the same side of; said cathode, a pluralityv of electrodes disposedbetween saidanodes and said cathode, and a focusing electrode extendingfrom adjacent one: I

of said anodes around said cathode but spaced therefromand to apositionadjacent the other said anode I 10. An electron 1 discharge device,comprising 1 an electron-emissive cathode, two narrow strip membersconnected together at their ends ,re-

mote from said tube, means connecting the end of each of said membersrespectively to one of,"

said electrodes, resonating means connecting said members, means toapply input potential to said electrodes, means including an impedance"connecting said bodies to said frameat a point.

substantially in electrical symmetry with respect to said frame, andoutput leads connected to the terminals of said impedance,

6. A circuit for high radio frequencies, comprising a discharge deviceas set forth in claim 1,

' said cathode," an accelerating electrode, control a resonant framehaving two parallel conductive members connected together attheir endsremote from said tube, means connecting the end, of; each of saidmembers respectively to one; of said electrodes, resonating means,connecting saidanodesfdisposed adjacent to but :spaced from each otherparallel to and substantially equidistant from said cathode on the sameside of said cathode, control electrodes. and accelerating T electrodessuccessively disposed, between said' anodes and said cathode,and afocusing elec- I trode extending from adjacent one of said anodes aroundsaid cathode but spaced therefrom and tea position adjacent the othersaid anode.

A ll. An electron discharge device, comprisinganelectron-emissive.:cathode, two narrow strip anodes disposed adjacentto but spaced from each other parallel toQand substantially equi-.distant from said cathodei on the" same side of electrodes, @andafarther accelerating electrode successively disposed between saidcathode and said anodes, and a focusing electrode extending g fromadjacent one of said anodes around'said cathode but spacedtherefrom andto a position adjacent the other said anode;

GEORGE E. PRAY.

SEBASTIAN moooBouo'.

. r 3 members, means to apply input potential to said f electrodes,means including an output impedance

